Clean Skies

Silence…the sound of flight to come?

Could the future of aviation see aircraft without greenhouse gas emissions or noise pollution?

The number of airplanes that are going to be flying in the next ten years is set to double. India, alone, plans to build 200 new airports in the next twenty years. With this sort of development, the industry has its work cut out – particularly in the face of emissions targets – to make cleaner aircraft. Currently it’s focusing on a number of areas including cleaner fuels, lighter aircraft (using carbon fiber composite), more efficient engines, and better air traffic management. All of these things taken together will help to keep emissions within the targets set by the industry and the regulators.

The video, article and infographic below explore the future of aerospace. Can we have cleaner skies, with zero emissions planes? What will it take to bring green aviation projects to a commercial scale? How can the 3DEXPERIENCE platform help companies who are creating these new airplanes reduce the time required to design, make, and certify new aircraft?

Will we ever fly in fuel-less planes?

Although no one can say with certainty what planes of the future will look like, one thing that is clear is that they will be better for the environment.

André Borschberg awakes from a 12 minute nap. His body aches for more sleep but the bite of the

-20˚C atmosphere jolts him into alertness. Some 7,500ft below him is the Pacific, to his left and right a horizon – its expanse amplified by his immediate surroundings. For up to six days at a time, in a space no larger than a telephone box, he sleeps, eats, goes to the toilet, practices yoga…and flies a fuel-less plane.

The former fighter pilot is currently taking turns with Swiss adventurer Bertrand Piccard to circumnavigate the Earth in a plane that is powered only by the sun.

Solar Impulse 2 (Si2) weighs as much as a car but has a wingspan greater than that of a Boeing 747. It’s basically a flying solar panel. The top of the wings, the fuselage and the tailplane have over 17,000 flexible solar cells embedded in them that charge the batteries to power the plane.

If all goes well, the aircraft should arrive back in the United Arab Emirates in July 2015, and the pilots will be feted for having broken a new world record – the longest distance ever flown by a solar airplane in aviation history.

Solar Impulse will no doubt be celebrated as an historic engineering feat and demonstration of human achievement, but will crowds awaiting the plane’s final touchdown be witnessing the dawn of a new era of clean aviation? The same kind of pivotal moment in flight history that crowds saw 88 years ago when Charles Lindbergh landed in Paris after a hot and delirious non-stop solo flight from New York?

Lindbergh’s flight represented the start of things to come in the development of commercial aviation, but even the Si2 pilots admit solar powered flight on a big scale might never take off.

Speaking from Chongqing in south-west China, Borschberg said: “We don’t see [building solar powered airliners] necessarily as an [environmental] priority because 3% of the CO2 is produced by air transportation and 97% by [land and sea transportation].

For Dimitri Mavris, professor of aerospace engineering at the Georgia Institute of Technology, it doesn’t even boil down to priorities. He believes that a complete replacement of current passenger jet aircraft with a purely solar powered alternative is not possible.

“Even futuristic battery technology or 100% efficient solar cells do not come close to what would be required to power a current conventional commercial jet aircraft,” he says.

Mavris believes that if we want to pursue solar flight we need to change how planes fly. “Planes would need to fly much slower and require large aircraft that can carry relatively little,” he says, “which is what the current experimental electric aircraft do.” Moreover, given passenger expectations on price and time this, he says, seems unlikely.

So what planes are on the horizon that use less or no fuel but which could be commercially feasible?

One small step

In the longer term, many aircraft makers are looking at electric and hybrid aircraft, the latter of which could reduce emissions from fuel by as much as 70%.

Airbus, for instance, is working on an electric plane called E-Fan. The company hopes that the E-Fan 2.0 – “the first certified, fully electric aircraft” – will go into production in 2017. But this is just a two-seater plane, and will only be able to stay in the air for an hour and a quarter before its lithium polymer batteries need a recharge. It’s not even intended to go into commercial light aviation. The idea is to learn how to scale up; create a smaller version of what will one day be the aircraft of tomorrow.

Each version of E-Fan is an incremental step towards the E-Thrust, a hybrid regional airliner that will use only electricity for propulsion. The plane is a hybrid because it will still need jet fuel for the power unit to recharge the batteries at cruising altitude.

But you’ll have to wait a few decades before you see an E-Thrust, or similar, at your local airport. “The hold back to many of these aircraft is certification,” says Jeff Smith, head of the Ideas Lab for aerospace & defence at global software leader, Dassault Systèmes.

“Once you go from something that's experimental, like Si2, to a commercial application, where you're talking about tens or hundreds of passengers, the game changes.”

For Michel Tellier, Dassault Systèmes’ vice president, aerospace and defence, the solution lies in simulation. “The more accurately and comprehensively we can simulate new technologies and concepts, the faster we can introduce them into the real world.

As a software partner to aerospace companies, we created our 3DEXPERIENCE platform to simulate everything from new nanostructures and complex systems to entire aircraft. This capability radically reduces the time it takes to conceptualise, design, fabricate and certify new aircraft

Michel TellierVP Aerospace & Defense, Dassault Systèmes

Lighten up

The company’s software can also help aircraft makers rapidly develop and certify the next generation of tough, lightweight materials.

Over the years, aircraft makers have been replacing aluminium parts with composite (plastic reinforced with carbon fibre) to make planes lighter and therefore more fuel efficient. Modern airliners are about 50% composite, but “there’s still room for improvement,” says Smith.

Dassault Systèmes simulated different materials for Si2 in order to match the plane’s strict weight criteria. Eventually the team simulated a model made primarily of carbon fibre composites, which was ultimately used. The plane had to be as light as possible while providing the lift needed at a cruising speed of around 90kph.

Researchers at Stanford University found that if planes were allowed to fly in formation, like migrating birds, they could reduce fuel use by 12%, even with two to five miles separating each plane in the formation

Learning from birds

Away from the world of high tech, one of easiest ways to cut fuel use is to improve air traffic management. According to Borschberg, better air traffic management systems would allow planes to land, taxi quicker, and take more direct routes.

Researchers at Stanford University found that if planes were allowed to fly in formation, like migrating birds, they could reduce fuel use by 12%, even with two to five miles separating each plane in the formation. The reason for this is, as planes fly, their wings create vortices that trail behind the wing. These vortices can be exploited by a plane flying above them. It gives the plane lift and helps cut down on fuel consumption.

Borschberg believes that, one day, planes will fly in formation without the need for air traffic management systems to co-ordinate them from the ground. “Planes will talk to each other and coordinate their flight paths between each other,” he says. “And I think you will see this in the next sixty years.” But even he can’t pinpoint what the plane of the future will look like. “If you look at the airplanes of the Wright brothers or Charles Lindbergh, it was difficult to believe that we would see 747s flying.”

Tellier sees future planes more as flying computers: “When we look at the likely forms they will take, future aircraft will be simpler in architecture yet much more sophisticated in the systems and technologies that are being used. They will be more efficient and intelligent than the current generation – a good metaphor to grasp this potential is to observe where cellular telephones have evolved over the past 20 years and recognize that aviation will likely follow a similar transformation.”

One thing that is certain, whether it’s down to lighter materials, ever more complex systems, batteries, or new flying formations, in 60 years we will undoubtedly be flying in cleaner planes that use much less fuel – if any at all.

What else in the horizon?

Shape shifters

There are a number of studies that investigate the additional efficiencies that could be gained from switching to a completely different shape. But aircraft with unconventional shapes that do not fit into the existing airport infrastructure will have very high barriers to entry since that would require large investments to change.

Hydrogen

Aircraft with this heavy fuel would require new engines and airframes and are unlikely to be seen for at least several decades. By then, however, we could be seeing something like the Zero Emission High Supersonic Transport (ZEHST) plane – made by Airbus Group (formerly EADS), Airbus’ parent company. The hydrogen powered jet can fly at near hypersonic speeds.

Made from plants

Whatever plane designs are on the horizon, and whichever formation they fly in, many aviation experts expect that liquid fuel will still be the favourite fuel for many years to come. With this in mind, some airlines are putting their weight behind biofuels. Most recently, The Boeing Company and partner South African Airways (SAA) pledged to use tobacco-based biofuel. Oil from the plant’s seeds will be converted into jet fuel in 2015, with an eventual test flight by SAA.

From hybrid to hydrogen powered planes….100 years of greener flight

In April 1979, the first manned aircraft to fly on solar power set off for a three minute journey, reaching 40ft (12m) and flying 0.5 miles (0.8 km). The aircraft’s pilot and creator, Larry Mauro, shortly afterwards told press that he wanted to improve on this model so that one day planes would “regularly take off and fly around all day on nothing but the solar-generated electricity that we're producing as we buzz along.”

Fast forward 35 years to the early hours of Monday 9 March 2015 when Solar Impulse 2 (Si2) is about to become the first aircraft to try to circumnavigate the Earth in an aircraft powered only by the sun’s rays.

But is, as Mauro anticipated, solar powered aircraft the future of aviation? Aviation experts say it’s highly unlikely that within our lifetimes we’ll be boarding solar powered planes. So, if not solar, what will the future of aviation look like? Read on to find out…

NOTE: The video, infographic and article were first published as an Advertisement Feature on bbc.com running from 29th June 2015 to 14th October 2015, and were created by the BBC Advertising Commercial Production team in partnership with Dassault Systèmes.